diff --git a/tests/include/tests/isc.h b/tests/include/tests/isc.h
index db80233070..33a510c364 100644
--- a/tests/include/tests/isc.h
+++ b/tests/include/tests/isc.h
@@ -94,7 +94,7 @@ teardown_managers(void **state);
 	int setup_test_##name(void **state ISC_ATTR_UNUSED);
 
 #define ISC_RUN_TEST_DECLARE(name) \
-	void run_test_##name(void **state ISC_ATTR_UNUSED);
+	static void run_test_##name(void **state ISC_ATTR_UNUSED);
 
 #define ISC_TEARDOWN_TEST_DECLARE(name) \
 	int teardown_test_##name(void **state ISC_ATTR_UNUSED)
@@ -123,9 +123,9 @@ teardown_managers(void **state);
 	int setup_test_##name(void **state ISC_ATTR_UNUSED); \
 	int setup_test_##name(void **state ISC_ATTR_UNUSED)
 
-#define ISC_RUN_TEST_IMPL(name)                             \
-	void run_test_##name(void **state ISC_ATTR_UNUSED); \
-	void run_test_##name(void **state ISC_ATTR_UNUSED)
+#define ISC_RUN_TEST_IMPL(name)                                    \
+	static void run_test_##name(void **state ISC_ATTR_UNUSED); \
+	static void run_test_##name(void **state ISC_ATTR_UNUSED)
 
 #define ISC_TEARDOWN_TEST_IMPL(name)                            \
 	int teardown_test_##name(void **state ISC_ATTR_UNUSED); \
@@ -137,9 +137,9 @@ teardown_managers(void **state);
 	;
 
 #define ISC_LOOP_TEST_CUSTOM_IMPL(name, setup, teardown)                   \
-	void run_test_##name(void **state ISC_ATTR_UNUSED);                \
-	void loop_test_##name(void *arg ISC_ATTR_UNUSED);                  \
-	void run_test_##name(void **state ISC_ATTR_UNUSED) {               \
+	static void run_test_##name(void **state ISC_ATTR_UNUSED);         \
+	static void loop_test_##name(void *arg ISC_ATTR_UNUSED);           \
+	static void run_test_##name(void **state ISC_ATTR_UNUSED) {        \
 		isc_job_cb setup_loop = setup;                             \
 		isc_job_cb teardown_loop = teardown;                       \
 		if (setup_loop != NULL) {                                  \
@@ -151,7 +151,7 @@ teardown_managers(void **state);
 		isc_loop_setup(mainloop, loop_test_##name, state);         \
 		isc_loopmgr_run(loopmgr);                                  \
 	}                                                                  \
-	void loop_test_##name(void *arg ISC_ATTR_UNUSED)
+	static void loop_test_##name(void *arg ISC_ATTR_UNUSED)
 
 #define ISC_LOOP_TEST_IMPL(name) ISC_LOOP_TEST_CUSTOM_IMPL(name, NULL, NULL)
 
diff --git a/tests/isc/mutex_test.c b/tests/isc/mutex_test.c
index d45c694aba..551030fe70 100644
--- a/tests/isc/mutex_test.c
+++ b/tests/isc/mutex_test.c
@@ -77,10 +77,11 @@ ISC_RUN_TEST_IMPL(isc_mutex) {
 #define CNT_MIN 800
 #define CNT_MAX 1600
 
-static size_t shared_counter = 0;
-static size_t expected_counter = SIZE_MAX;
+#if !defined(__SANITIZE_THREAD__)
 static isc_mutex_t lock;
 static pthread_mutex_t mutex;
+static size_t expected_counter = SIZE_MAX;
+static size_t shared_counter = 0;
 
 static void *
 pthread_mutex_thread(void *arg) {
@@ -203,6 +204,7 @@ ISC_RUN_TEST_IMPL(isc_mutex_benchmark) {
 
 	isc_mem_cput(mctx, threads, workers, sizeof(*threads));
 }
+#endif
 
 ISC_TEST_LIST_START
 
diff --git a/tests/isc/rwlock_test.c b/tests/isc/rwlock_test.c
index 2fae39256d..b656997919 100644
--- a/tests/isc/rwlock_test.c
+++ b/tests/isc/rwlock_test.c
@@ -52,9 +52,11 @@ static isc_barrier_t barrier2;
 #define CNT_MIN 800
 #define CNT_MAX 1600
 
+#if !defined(__SANITIZE_THREAD__)
 static size_t shared_counter = 0;
 static size_t expected_counter = SIZE_MAX;
 static uint8_t boundary = 0;
+#endif
 static uint8_t *rnd;
 
 static int
@@ -133,6 +135,7 @@ ISC_RUN_TEST_IMPL(isc_rwlock_wrlock) {
 /*
  * Simple single-threaded lock/tryupgrade/unlock test
  */
+#if !defined(__SANITIZE_THREAD__)
 ISC_RUN_TEST_IMPL(isc_rwlock_tryupgrade) {
 	isc_result_t result;
 	isc_rwlock_lock(&rwlock, isc_rwlocktype_read);
@@ -341,6 +344,7 @@ ISC_RUN_TEST_IMPL(isc_rwlock_benchmark) {
 
 	isc_mem_cput(mctx, threads, workers, sizeof(*threads));
 }
+#endif
 
 ISC_TEST_LIST_START
 
diff --git a/tests/isc/spinlock_test.c b/tests/isc/spinlock_test.c
index 89db288774..169dc41b81 100644
--- a/tests/isc/spinlock_test.c
+++ b/tests/isc/spinlock_test.c
@@ -82,6 +82,7 @@ ISC_RUN_TEST_IMPL(isc_spinlock) {
 #define CNT_MIN 800
 #define CNT_MAX 1600
 
+#if !defined(__SANITIZE_THREAD__)
 static size_t shared_counter = 0;
 static size_t expected_counter = SIZE_MAX;
 
@@ -213,6 +214,7 @@ ISC_RUN_TEST_IMPL(isc_spinlock_benchmark) {
 
 	isc_mem_cput(mctx, threads, workers, sizeof(*threads));
 }
+#endif
 
 ISC_TEST_LIST_START